EXTERNAL TRANSMISSION/RECEPTION APPARATUS, TRANSMISSION/RECEPTION SYSTEM, AND TRANSMISSION/RECEPTION METHOD

摘要

PROBLEM TO BE SOLVED: To detect a location in which a wireless transmission device is present.

SOLUTION: An external transmission/reception apparatus 10 transmits a transmission signal. A wireless transmission device 20 is activated when it receives a transmission signal from the external transmission/reception apparatus 10, and transmits a reply signal at an amplitude level corresponding to that of the transmission signal. ID information is written in the reply signal. Furthermore, the external transmission/reception apparatus 10 determines a distance (communication distance) between itself and the wireless transmission device based on a status (such as an amplitude level) of a reply signal when it receives the reply signal from the wireless transmission device 20.

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